Alfredo Moser's invention is lighting up the world. In 2002, the Brazilian mechanic had a light-bulb moment and came up with a way of illuminating his house during the day without electricity - using nothing more than plastic bottles filled with water and a tiny bit of bleach.

"An engineer came and measured the light," he says. "It depends on how strong the sun is but it's more or less 40 to 60 watts," he says.

The inspiration for the "Moser lamp" came to him during one of the country's frequent electricity blackouts in 2002. "The only places that had energy were the factories - not people's houses," he says, talking about the city where he lives, Uberaba, in southern Brazil.